ML15034A136
| ML15034A136 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 02/03/2015 |
| From: | Thadani M Plant Licensing Branch 1 |
| To: | Harding T Exelon Corp |
| References | |
| Download: ML15034A136 (2) | |
Text
1 NRR-PMDAPEm Resource From:
Thadani, Mohan Sent:
Tuesday, February 03, 2015 8:25 AM To:
Harding Jr, Thomas:(GenCo-Nuc); Cates, Laura:(GenCo-Nuc)
<Laura.Cates@exeloncorp.com> (Laura.Cates@exeloncorp.com)
Subject:
Ginna NFPA-805-Probabilistic Risk Assessment (PRA) RAI 19.03 Tom and Laura:
As a follow up to our phone call for Ginna NFPA-805 PRA, we have finalized our question (PRA) RAI 19.03 as follows. Please provide your response within 30 days from the date of this email.
Thanks.
Mohan C Thadani Senior Project Manager Millstone, Ginna, and Exelon Northeast Fleet Plant Licensing Branch I-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation (301) 415-1476 Mohan.Thadani@nrc.gov Probabilistic Risk Assessment (PRA) RAI 19.03 The FAQ 08-0048 sensitivity analysis on fire ignition frequencies was performed in response to PRA RAI 19 and the results showed that the acceptable delta-CDF [core damage frequency] was substantively exceeded.
Based on this result, FAQ 08-0048 guidance is that the licensee consider fire protection, or related, measures that can be taken to provide additional defense-in-depth. The Fire PRA credits both the planned modifications as well as existing equipment associated with shutdown panels ABELIP and IBELIP. These modifications, equipment, and associated operator actions are credited in the reported delta-CDF and therefore do not provide additional defense-in-depth. Additional defense-in-depth including FLEX equipment and controls for high risk fire areas was discussed in response to PRA RAI 19.1.1. However, it is not clear that this additional defense-in-depth was sufficient or even addressees the risk drivers contributing to delta-CDF exceeding the acceptance guidelines. The response to PRA RAI 19.1.1 also stated that a component-based frequency would decrease the main control board risk. The use of plant-wide frequency is an integral part of all current fire PRAs and alternatives are not within the scope of plant-specific license amendment request reviews.
Consistent with acceptable methods including FAQ 08-0048, provide one of the following:
Identify additional defense-in-depth measures which address the risk contributors commensurate with the magnitude of the exceedance of the delta-CDF acceptance guidelines in the sensitivity study.
Discuss plant-specific characteristics, which, if modelled more realistically consistent with acceptable fire PRA methods, would decrease the sensitivity study risk increase to below the Regulatory Guide 1.174 acceptance guidelines.
Perform additional analysis using acceptable NFPA 805 fire PRA methods (or propose additional modifications) until the change-in-risk from the sensitivity study does not exceed the acceptance guidelines.
Hearing Identifier:
NRR_PMDA Email Number:
1850 Mail Envelope Properties (Mohan.Thadani@nrc.gov20150203082500)
Subject:
Ginna NFPA-805-Probabilistic Risk Assessment (PRA) RAI 19.03 Sent Date:
2/3/2015 8:25:25 AM Received Date:
2/3/2015 8:25:00 AM From:
Thadani, Mohan Created By:
Mohan.Thadani@nrc.gov Recipients:
"Harding Jr, Thomas:(GenCo-Nuc)" <thomas.hardingjr@exeloncorp.com>
Tracking Status: None "Cates, Laura:(GenCo-Nuc) <Laura.Cates@exeloncorp.com> (Laura.Cates@exeloncorp.com)"
<Laura.Cates@exeloncorp.com>
Tracking Status: None Post Office:
Files Size Date & Time MESSAGE 2590 2/3/2015 8:25:00 AM Options Priority:
Standard Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
Recipients Received: